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Exploring cyanobacterial diversity in Antarctica Blog

2 Posts tagged with the labyrinth tag
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Most of the cyanobacterial mats that we have found were orange pigmented and the macroscopic structure was flaky to cohesive. The orange colour is due to carotenoids which are an protection against UV and oxidative stress.

 

I had a small light micrscope with me in the field and the genus Leptolyngbya dominated the orange mats. Leptolyngbya are filamentous non-branching cyanobacteria belonging to the order Oscillatoriales. They are mostly between 0.5-3 micrometre thick. However, the lower side of the orange layers sometimes had green pigmentation, which besides the Leptolyngbya also had some Phormidium. The genus Phormidium also belong to the order Oscillatoriales, but they are thicker with a width of around 5 micrometres.

 

   Flaky orange-pigmented cyanobacterial mats dominated by Leptolyngbya

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Cohesive orange-pigmented cyanobacterial mats

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green lower side of cyanobacterial mat with Phormidium

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Interestingly, we also found some cyanobacterial mats which were dark purple to black. This colour is due to the UV-screening Scytonemin. We found the genus Schizothrix sp. (Oscillatoriales)  in the mats which is known to produce Scytonemin. We also found several ponds with large accumulations of the genus Nostoc, which belongs to the order Nostocales and has specialist cells called heterocysts for nitrogen-fixation.

 

Cyanobacterial mats with the Scytonemin-producing genus Schizothrix

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Nostoc accumulations in a meltwater pond

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We also found a few ponds with green algae. Green algae biofilms are easy to distinguish from cyanobacteria as green algae are very bright green.

                                                                                              

Green algae

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The Wright Valley is one of the ice-free Dry Valleys. The Upper Wright valley is characterised by the so-called Labyrinth, which is an area of steep-sided canyons and channels. It is mainly dolerite and most rocks are bright red. Based on the literature it was formed by large 'floods during the mid-Miocene era'.

 

The Labyrinth

 

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In the area you can find many strangely shaped rocks. They are called ventifacts, and are wind- and dirt-sculpted rocks.

 

Ventifacts in the Labyrinth

 

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Wherever you look you only see rocks and it often reminded me of images showing how it may look on Mars.

 

 

Landscapes like on Mars

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However, there is life. On one of our walks, we found these lichens. They were on the top of one of the ridges, where the overall humidity seems to be higher due to its location at a height of greater than 750 metres, and the greater influence of clouds and fog. Many of the lichens grow under or in cracks of the rocks, and this enhances the erosion of the rocks.

 

 

Lichens on rocks in the Labyrinth

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AND, as soon as you get running water and temporary ponds you get thick accumulations of orange-pigmented mats. To date there have only been few morphological descriptions and there is no DNA-based data available at all.

 

 

Meltwater ponds covered by ice with bright orange mats

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Orange cyanobacterial-based microbial mats

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Close-up of microbial mat

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